Organic lighting emitting display device including light absorbing layer and method for manufacturing same

ABSTRACT

A method of preparing a display device including a plurality of pixels where a plurality of gate lines cross a plurality of data lines, respectively, each of the pixels including a thin film transistor (TFT) region and a display region, the method can include: forming a thin film transistor (TFT) in the TFT region; and forming a light emitting element for displaying images based on signals from the TFT in the display region, in which a metallic layer is disposed in the TFT region for electrical connection of the TFT; and a light absorbing layer configured to absorb at least part of light propagating toward the metallic layer is disposed on the metallic layer between the metallic layer and one of a gate insulating layer, an active layer, an interlayer dielectric layer and a substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of co-pending U.S. application Ser. No.14/567,719, filed on Dec. 11, 2014, which claims priority from and thebenefit under 35 U.S.C. §119(a) of Korean Patent Application No.10-2014-0105778, filed on Aug. 14, 2014. All of these applications arehereby incorporated by reference for all purposes as if fully set forthherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic light emitting display fordisplaying an image and having a light absorbing layer combined therein,and a method of manufacturing the same.

2. Description of the Related Art

As the information society develops, display devices for displaying animage are being increasingly required in various forms, and in recentyears, various display devices such as Liquid Crystal Displays (LCDs),Plasma Display Panels (PDPs), and Organic Light Emitting Display Devices(OLEDs) have been utilized. Each of such various display devicesincludes a display panel proper for the display device.

The display panel included in such a display device may be one ofmultiple display panels made from one substrate. That is, according tovarious processing procedures, elements constituting pixels, signallines, and power lines are first formed in units of display panels inone substrate, and the substrate is then cut using a scribing equipmentin units of the display panels, so as to produce a plurality of displaypanels.

Light incident to a display device from the outside thereof is reflectedby elements, such as wire lines, constituting the display device, andthen escapes the display device. This outgoing reflected light mayoverlap with an image output by the display device to degrade thequality of the image. Therefore, a technology for reducing thereflection of incident light is necessary.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the present application are directed to adisplay device and a preparing method thereof that substantially obviateone or more of problems due to the limitations and disadvantages of therelated art. According to one aspect of the embodiments, a displaydevice includes a plurality of pixels where a plurality of gate linescross a plurality of data lines, respectively, each of the pixelsincluding a thin film transistor (TFT) region and a display region; aTFT formed in the TFT region; light emitting elements formed in thedisplay region for displaying images based on signals from the TFT; ametallic layer disposed in the TFT region for electrical connection ofthe TFT; and a light absorbing layer disposed on the metallic layer andconfigured to absorb at least part of light propagating toward themetallic layer.

A method of preparing a display device according to another aspect ofthe present embodiments includes: forming a thin film transistor (TFT)in a TFT region; and forming a light emitting element for displayingimages based on signals from the TFT in the display region, wherein ametallic layer is disposed in the TFT region for electrical connectionof the TFT, and wherein a light absorbing layer configured to absorb atleast part of light propagating toward the metallic layer is disposed onthe metallic layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 schematically illustrates a display device to which embodimentsof the present invention are applied;

FIG. 2 illustrates a part of a display panel to which the presentinvention is applied;

FIG. 3 illustrates a structure in which a light absorbing layer and aphase compensation layer are laminated on a light shield layer formed ona substrate according to an embodiment of the present invention;

FIG. 4 illustrates a structure in which a light absorbing layer and aphase compensation layer are laminated on a gate according to anembodiment of the present invention;

FIGS. 5A to 5C illustrate a process of laminating a light absorbinglayer on a source electrode and a drain electrode, and a laminatedstructure, according to an embodiment of the present invention;

FIG. 6 illustrates a structure of a thin-film transistor on which aphase compensation layer is deposited using the process of FIGS. 5A to5C;

FIGS. 7A and 7B illustrate a structure for reducing reflection ofexternal light in a light absorbing layer and a phase compensation layeraccording to an embodiment of the present invention;

FIG. 8 is a graph depicting relationships between a reflectance and awavelength according to an embodiment of the present invention and therelated art; and

FIG. 9 is a flowchart illustrating a process of forming a lightabsorbing layer on a light shield layer and a wiring area according toan embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the accompanying drawings. In the followingdescription, the same elements will be designated by the same referencenumerals although they are shown in different drawings. Further, in thefollowing description of the present invention, a detailed descriptionof known functions and configurations incorporated herein will beomitted when it may make the subject matter of the present inventionrather unclear.

In addition, terms, such as first, second, A, B, (a), (b) or the likemay be used herein when describing components of the present invention.Each of these terminologies is not used to define an essence, order orsequence of a corresponding component but used merely to distinguish thecorresponding component from other component(s). In the case that it isdescribed that a certain structural element “is connected to”, “iscoupled to”, or “is in contact with” another structural element, itshould be interpreted that another structural element may “be connectedto”, “be coupled to”, or “be in contact with” the structural elements aswell as that the certain structural element is directly connected to oris in direct contact with another structural element.

FIG. 1 schematically illustrates a display device to which embodimentsof the present invention are applied.

Referring to FIG. 1, the display device 100 according to an embodimentof the present invention includes a display panel 110 in which aplurality of first lines VL1 to VLm are formed in a first direction (forexample, a vertical direction) and a plurality of second lines HL1 toHLn are formed in a second direction (for example, a horizontaldirection), a first driving unit 120 for supplying a first signal to theplurality of first lines VL1 to VLm, a second driving unit 130 forsupplying a second signal to the plurality of second lines HL1 to HLn,and a timing controller 140 for controlling the first driving unit 120and the second driving unit 130.

In the display panel 110, a plurality of pixels P are defined by theplurality of first lines VL1 to VLm formed in the first direction (forexample, a vertical direction) and the plurality of second lines HL1 toHLn formed in the second direction (for example, a horizontal direction)crossing each other.

Each of the first driving unit 120 and the second driving unit 130 mayinclude at least one driver Integrated Circuit (IC) that outputs asignal for image display.

The plurality of first lines VL1 to VLm formed in the first direction inthe display panel 100 may be, for example, data lines formed in thevertical direction (first direction), for transferring a data voltage(first signal) to vertical rows of pixels, and the first driving unit120 may be a data driving unit for supplying a data voltage to the datalines.

The plurality of second lines HL1 to HLn formed in the second directionin the display panel 110 may be gate lines formed in the horizontaldirection (second direction), for transferring a scan signal (firstsignal) to horizontal rows of pixels, and the second driving unit 130may be a gate driving unit for supplying a scan signal to the gatelines.

Further, a pad unit for connection with the first driving unit 120 andthe second driving unit 130 is arranged in the display panel 110. Whenthe first driving unit 120 supplies a first signal to the plurality offirst lines VL1 to VLm, the pad unit transfers the first signal to thedisplay panel 110. In the same manner, when the second driving unit 130supplies a second signal to the plurality of second lines HL1 to HLn,the pad unit transfers the second signal to the display panel 110.Therefore, the pad unit may be simultaneously formed in the process offorming areas of the pixels of the display panel 110.

Meanwhile, a display device using organic electrofluorescence among thedisplay devices as shown in FIG. 1 may apply a polarizing plate or apolarizing film capable of shield reflection by each electrode unit.

FIG. 2 illustrates a part of a display panel to which the presentinvention is applied. FIG. 2 illustrates a part of a display panel inwhich no polarizing plate is used.

A thin-film transistor area 291 on a substrate 200 includes a lightshield layer 202, buffer layers 204 and 206, an active layer 210 and agate insulation layer 215, a gate 220, and an InterLayer Dielectic (ILD)layer 225, and the ILD layer is partially etched so that the activelayer 210 is exposed, and a source/drain electrode 230 is connectedthereto. Further, a passivation layer 235, an overcoat layer 240, and abank 245 are formed. Meanwhile, a pixel area 292 has a pixel electrode280, and an organic layer (organic light emitting layer) 285 formedtherein, and is configured by a cathode electrode 290. An RGB area hasred/green/blue color filters 251, 253 and 254, and a white pixel area252 does not have a separate color filter formed therein.

In FIG. 2, although the pixel area illustrates all of four pixels forthe convenience of the description, each of the four pixels can dividethe organic layers 285 by a bank, and each of the pixel electrodes 280can be connected to a thin-film transistor area on each of the RWGBareas 251, 252, 253 and 254.

In FIG. 2, a polarizing plate or a polarizing film for reducingreflection of external light (the incident light from the outside) maynot be used, so that beams 298 a and 298 b of light introduced from theoutside are reflected to paths 299 a and 299 b by wiring such as asource/drain electrode 230 and a light shielding layer 202.

An example of a method for reducing reflection of non-polarized externallight at a metal part such as the wiring corresponds to a scheme ofcoating a material such as a Black Matrix (BM) to reduce reflectiongenerated at a metal. That is, in order to form a low-reflection patternthrough external light absorption, a pattern may be formed after anorganic BM layer is coated, or a pattern may be formed by depositing aninorganic BM having the thickness of several microns. These schemesconsume a lot of processing time, and increase manufacturing costsneeded for forming the BM. Further, in a case of an organic lightemitting display panel having a bottom emission structure, when aThin-Film Transistor (TFT) is manufactured after the BM pattern, afollowing heat process (at a temperature of 300° C. or more) should beperformed, so that there is a limitation in use of the organic BM, etc.

That is, a technology of forming a BM for reducing reflection ofexternal light needs to secure the thickness for absorbing the externallight. When the organic BM is coated to have a thickness of about 5-6um, the reflectance of 10% or lower can be secured. Further, when aninorganic BM is coated to have a thickness of about 3-4 um, thereflectance of 10% or lower can be secured. However, a material having aheat-resisting property and a processing time are required, and when theinorganic BM is deposited, a lot of time is consumed for depositionusing sputtering, so that it is difficult to secure a mass productiontechnology of the process.

Hereinafter, in an embodiment of the present invention, examples of amaterial laminated on a light absorbing layer in order to reducereflection of non-polarized external light correspond to an alloy oxidemade of a metal and two or more of a copper oxide, a nickel oxide, amolybdenum oxide, or copper/nickel/molybdenum. The reflectance ofexternal light at a metal can be reduced to 10% or lower, by depositingthe aforementioned material on a light absorbing layer, or by forming adual layered structure by using a light absorbing layer and a phasecompensation layer. As an example of the phase compensation layer, atransparent oxide having a refractive index similar to that of a copperoxide may be applied, and a phase compensation layer provides an effectof further reducing the reflectance over all wavelength areas. Thethickness of the light absorbing layer and the phase compensation layeraccording to the present invention is preferably 500 to 1000 Å, whichprovides a low reflection effect by improving an optical absorptivityand generating a phase-difference interference of the external lightthrough the dual-layered structure.

Hereinafter, a display device in which a copper oxide is deposited on anarea for reflecting external light, such as wiring including electricalconnection lines and electrodes, which corresponds to an embodiment of alow reflective material for the aforementioned light absorbing layer,will be described. Although the copper oxide will be described in thefollowing description, the present invention is not limited thereto, anda metal oxide which is applicable in consideration of a refractive indexand an extinction coefficient can be applied to an embodiment of thepresent invention. Although examples in the present invention where thelight absorbing layer is deposited correspond to a gate, a sourceelectrode, a drain electrode, a light shield layer, etc., the presentinvention is not limited thereto, and the light absorbing layer may bedisposed on all areas from which external light can be reflected.

In the present invention, low reflection of external light is achievedby removing a polarizing film or a polarizing plate and by laminating asingular metal oxide such as a copper oxide, as a light absorbing layer,on a source/drain electrode and a gate corresponding to a metal wiringof a thin-film transistor area, and a light shield area. Further, aphase compensation layer (phase-difference compensation layer) forperforming a phase-difference compensation function through destructiveinterference may be laminated on the light absorbing layer in order tosecure a lower reflectance for external light. Although SN, IGZO, ITO,etc. may constitute the phase compensation layer, the present inventionis not limited thereto. In the present invention, a low reflectivedisplay panel on which the light absorbing layer is laminated and thephase compensation layer is selectively laminated will be described indetail.

FIG. 3 illustrates a structure in which a light absorbing layer and aphase compensation layer are laminated on a light shield layer formed ona substrate according to an embodiment of the present invention. Astructure of the entirety of the panel has been described in FIGS. 1 and2, so that a part to which an embodiment of the present invention isapplied will be enlarged and illustrated. An embodiment 301 correspondsto an embodiment where a light absorbing layer is formed on a lightshield layer, and an embodiment 302 corresponds to an embodiment whereina light absorbing layer and a phase compensation layer are formed as adual layer.

In the embodiment 301, a buffer layer 204 is formed on a substrate 200,and a light absorbing layer 301 a is disposed on the buffer layer 204.Further, a light shield layer 202 is disposed on a light absorbing layer310 a. In the embodiment 301, the buffer layer may be selectivelyformed. The light absorbing layer 301 a is disposed between a lightshield layer 202 and the substrate, and when a material of the lightabsorbing layer 310 has an excellent deposition force with respect tothe substrate 200, the buffer layer 204 may not be formed. The lightabsorbing layer 310 a absorbs external light introduced through thesubstrate 200, thereby reducing reflection of external light caused bythe light shield layer 202 in the display panel in which a polarizingfilm or a polarizing plate is not formed.

The light absorbing layer 310 a may be formed using a mask (photoresist) required for forming the light shield layer 202. The lightabsorbing layer 310 a is deposited under the light shield layer 202, andin a manufacturing process, the light absorbing layer 310 a is firstformed using the same mask, and the light shield layer 202 may then beformed.

In the embodiment 302, the buffer layer 204 is formed on the substrate200, and a phase compensation layer 320 a is disposed on the bufferlayer 204. Further, the light absorbing layer 310 a and the light shieldlayer 204 are disposed on the phase compensation layer 320 a. In theembodiment 302, the buffer layer 204 may be selectively formed. Thephase compensation layer 320 a is disposed between the light absorbinglayer 301 and the substrate 200, and when a material of the phasecompensation layer 320 a has an excellent deposition force with respectto the substrate 204, the buffer layer 204 may not be formed. The phasecompensation layer 320 a compensates a phase of light. The lightabsorbing layer 310 a absorbs external light introduced through thesubstrate 200, and the light that is not absorbed by the light absorbinglayer 310 a has a phase changed by the phase compensation layer 320 aand passes toward the substrate 200. In this process, the light with thechanged phase is canceled by the light introduced from the substrate,and consequentially the light that is not absorbed by the lightabsorbing layer 310 a is not reflected, either.

In the embodiment 302, the light absorbing layer 310 a and the phasecompensation layer 320 a may be formed using a mask (photo resist)needed for forming the light shield layer 202. Both the light absorbinglayer 310 a and the phase compensation layer 320 a are deposited underthe light shield layer 202, and in a manufacturing process, beforeforming the light shield layer 202, the phase compensation layer 320 ais first formed using the same mask, the light absorbing layer 310 a isformed on an area where the phase compensation layer 320 a, and thelight shield layer 202 is then formed.

The thickness of the phase compensation layer may be configured inproportion to the wavelength of external light and in inverse proportionto the refractive index of the light absorbing layer. The external lightcorresponds to a visible ray, so that in accordance with an embodiment,the thickness of the phase compensation layer may be configured inproportion to a central wavelength band in the wavelength band of thevisible ray. In another embodiment, the thickness of the phasecompensation layer may be configured in proportion to a specificwavelength band in consideration of the visible sense of the displaypanel in the wavelength band of the visible ray.

FIG. 4 illustrates a structure in which a light absorbing layer and aphase compensation layer are laminated on a gate according to anembodiment of the present invention. The entirety of the panel has beenillustrated in FIGS. 1 and 2, so that a part to which an embodiment ofthe present invention is applied is enlarged and illustrated.

In an embodiment 401, an active layer 210 is formed on a buffer layer206, and a gate insulation layer 215 is disposed on the active layer.Further, a light absorbing layer 310 b is formed on the gate insulationlayer 215. A gate 220 is disposed on the light absorbing layer 310 b. Inthe embodiment 401, the buffer layer 206 may be selectively formed. Thelight absorbing layer 310 b absorbs external light introduced from theoutside, thereby reducing reflection of the external light by the gate220 of the display panel in which a polarizing film or a polarizingplate is not formed.

The light absorbing layer 310 b may be formed using a mask (photoresist) needed for forming the gate 220. The light absorbing layer 310 bis deposited under the gate 220, and in a manufacturing process, beforethe gate is formed, the light absorbing layer 310 is first formed usingthe same mask, and the gate 220 is then formed.

In an embodiment 402, the active layer 210 is formed on the buffer layer206, and the gate insulation layer 215 is disposed on the active layer210. A phase compensation layer 320 b and a light absorbing layer 310 bare formed on the gate insulation layer 215. The gate 220 is disposed onthe light absorbing layer 310 b. In the embodiment 402, the buffer layer206 may be selectively formed. The light absorbing layer 310 b and thephase compensating layer 320 b absorb external light introduced from theoutside, thereby reducing reflection of the external light by the gatein the display panel in which a polarizing film or a polarized plate.

The phase compensation layer 320 b and the light absorbing layer 310 bmay be formed using a mask (photo resist) needed for forming the gate220. The light absorbing layer 310 b is deposited under the gate 220,and in a manufacturing process, before the gate 220 is formed, the phasecompensation layer 320 b is first formed using the same mask, and thelight absorbing layer 310 b is formed thereon, and the gate 220 is thenformed. The aforementioned phase compensation layer of FIG. 3 can beapplied to the phase compensation layer of FIG. 4.

Although the gate is mainly described in FIG. 4, the gate is not limitedthereto, and includes wiring simultaneously formed of a gate materialtogether with the gate. That is, in the present invention, the gateincludes the wiring formed together with the gate as well as the gate ofa transistor.

FIGS. 5A to 5C illustrates a process of laminating a light absorbinglayer on a source electrode and a drain electrode and a laminatedstructure according to an embodiment of the present invention. Thestructure of the entirety of the panel has been illustrated in FIGS. 1and 2, so that a part to which an embodiment of the present invention isapplied is enlarged and described.

In FIG. 5A, after the active layer 210, the gate insulation layer 215,and the gate 220 are formed, the ILD layer 225 is formed, and a lightabsorbing layer 310 c is formed on the ILD layer 225. When the lightabsorbing layer 310 c is formed, a mask (photo resist) for a sourceelectrode and a drain electrode to be later deposited may be used.

FIG. 5B is a view in which a contact hole for forming a source electrodeand a drain electrode is formed. The light absorbing layer 310 c, theILD layer 225, and the buffer layer 206 are etched, and contact holes501 a, 501 b and 501 c are formed to expose the active layer 210 and thelight shield layer 202.

FIG. 5C is a view in which a source electrode and a drain electrode(230) are formed using the same mask as that of the light absorbinglayer 310 c formed in FIG. 5A. The light absorbing layer 310 c formedunder the source electrode and the drain electrode 230 absorbs externallight introduced from the outside, thereby reducing reflection of theexternal light by the source electrode and the drain electrode 230 inthe display panel in which a polarized film or a polarized plate is notformed.

Although not illustrated in the drawings, before the light absorbinglayer is formed, a phase compensation layer may be formed using the mask(photo resist) for the source electrode and the drain electrode.

Although the source and drain electrodes are mainly described in FIGS.5A to 5C, the source electrode and the drain electrode are not limitedthereto, and include all wiring formed of a material constituting thesource electrode and the drain electrode together with the source anddrain electrodes at the same time. That is, in the present invention,the source and drain electrodes include all the wiring simultaneouslyformed together with the source and drain electrodes as well as thesource and drain electrodes of the transistor.

FIG. 6 illustrates a structure of a thin-film transistor on which aphase compensation layer is deposited in the same manufacturing processas that of FIGS. 5A to 5C. Even in the light shield layer 202 and thegate 220, the phase compensation layers 320 a and 320 b are firstdeposited, and the light absorbing layers 310 a and 310 b are deposited.Also, a phase compensation layer 320 c and a light absorbing layer 310 care formed under the source electrode and the drain electrode 230. Theaforementioned phase compensation layer of FIG. 3 can be applied to FIG.6.

FIGS. 7A and 7B illustrate a structure for reducing reflection ofexternal light by a light absorbing layer and a phase compensation layeraccording to an embodiment of the present invention. Although FIGS. 7Aand 7B illustrate a structure of a low reflective OLED using a bottomemission scheme, the present invention is not limited thereto, and thestructure of FIGS. 7A and 7B can be applied to panels having variousstructures. That is, the structure of FIGS. 7A and 7B is applicable toall panels which do not employ a polarizing film or a polarizing plateand have a characteristic in which external light is reflected bywiring.

The panel to which the structures of FIGS. 7A and 7B are applied has aplurality of data lines and a plurality of gate lines disposed therein,and includes an active layer formed by intersecting the data lines andthe gate lines as a thin-film transistor area, a plurality of thin-filmtransistors including a gate in which a light absorbing layer isselectively disposed and a source electrode and a drain electrode inwhich a light absorbing layer is selectively disposed, a light shieldlayer in which a light absorbing layer is selectively disposed whilefacing the thin-film transistor, and a plurality of pixel electrodesconnected to a source electrode or a drain electrode of the thin-filmtransistor. Further, the fact that the data driving unit and the gatedriving unit for driving a data line and a gate line of the displaypanel are disposed within the display device has been previouslydescribed in FIG. 1. Furthermore, in FIGS. 3 to 6, the light absorbinglayer selectively formed in one or more of the gate, the sourceelectrode, the drain electrode, and the light shield layer may be formedof a metal oxide or an alloy oxide, or the phase compensation layer maybe coupled to such a light absorbing layer, and the extinctioncoefficient of the complex reflective index of a metal or an alloyconstituting the light absorbing layer may be 0.4 or more.

Here, the complex reflective index is calculated in a form of “n+ik”. Asa value obtained by applying the value n and the value k is larger, amaterial can absorb a larger quantity of light. The value k of thecomplex reflective index which is larger than zero implies that thematerial is opaque. In the present specification, when the lightabsorbing layer is formed of a metal oxide having the extinctioncoefficient k of the complex reflective index which is equal to orlarger than 0.4, the reflection can be reduced by absorbingnon-polarized external light. That is, the extinction coefficient of thecomplex reflective index is configured as being 0.4 or larger, therebyimproving a low reflective effect by the reflection. In more detail, thelight absorbing layer formed on the light shielding layer, the gate, thesource electrode, and the drain electrode is formed of a metal, a metaloxide, or an alloy oxide, thereby not affecting electric flow whilereducing the reflection of the external light. Further, the mask neededfor forming the light shield layer, the gate, the source electrode, andthe drain electrode is equally applied to the light absorbing layer, sothat a separate mask is not used in a manufacturing process, therebyreducing a manufacturing time and manufacturing costs.

When the reflective index of a copper oxide (CuOx) according to anembodiment of the present invention is calculated, in a case where awavelength of light is 550 nm, the value n is 2.58 and the value k is0.59. Meanwhile, when the reflective index of a nickel oxide (NiOX)according to an embodiment of the present invention is calculated, in acase where a wavelength of light is 550 nm, the value n is 2.79, and thevalue k is 0.43. Further, oxides formed of an alloy of two or more of aplurality of metals, e.g., three metals of copper, nickel and molybdenummay be employed as the light absorbing layer. In this case, the lightabsorbing layer may be formed of an oxide alloyed with copper (Cu-Alloyoxide) or an oxide alloyed with nickel (NiMoOx). Further, the compoundmaterial having the reflective index of the alloyed material of whichthe value n is 2.0 or larger and the value k is 0.4 or larger is appliedas the light absorbing layer, thereby improving light absorptivity.

When the present invention is applied, the light absorbing layer may beformed of a single oxide or a alloy oxide. Further, as an embodiment, alow reflective wiring can be implemented only by applying the singleoxide such as copper oxide, nickel oxide and molybdenum oxide having thethickness of 1000 Å or thinner

Further, an oxide may be deposited to have the thickness of 1 micrometer or thinner, and the mask used for wiring may be continuously used,thereby reducing manufacturing costs and simplifying the manufacturingprocess. A polarizing plate or a polarizing film is removed, therebyimproving an efficiency of the panel and a lifespan of the element, andat the same time, the light absorbing layer is applied to a productrequiring a low reflective wiring, thereby improving a visual sense.

In accordance with an embodiment of the present invention, when a metaloxide or an alloy oxide having the extinction coefficient k which is 0.4or larger and selectively having the value n of the reflective indexwhich is 2 or larger, in the complex reflective index having a form of“n+ik”, is deposited, external light is refracted, thereby providing alow reflective effect. Especially, an example of metals which can bedeposited for low reflection may correspond to one of copper, nickel andmolybdenum, and an alloy generated by selecting two or more of them alsoprovides a low reflective effect. These metals provide effects in thatan efficiency of a heating process or a manufacturing process isimproved while maintaining conductivity of wiring and an electrode, sothat the light absorbing layer is maintained to have a low reflectivecharacteristic as well as an electric characteristic of otherwiring/electrodes of when a low reflective material is deposited,without damage.

In FIGS. 7A and 7B, a light penetration adjustment film 780 isadditionally cemented to the substrate 200. The light penetrationadjustment film 780 can adjust the penetration ratio of light to adjustthe penetration ratio of light emitted from an organic element and thereflectance of external light. The light penetration adjustment film 780can be selectively coupled to the substrate.

FIG. 7A illustrates a structure of a thin-film transistor where theaforementioned light absorbing layer 310 is disposed. Although anembodiment of FIG. 7A is that a material of light absorbing layers 310a, 310 b and 310 c corresponds to copper oxide, the light absorbinglayers may be formed using a material having a high light absorbingefficiency and a conductivity, such as manganese, nickel, titanium, etc.

In FIG. 7A, the light absorbing layers may use a pattern to form a metalmaterial at a location where each of them is formed, according to thecorresponding location. For example, the light absorbing layer 310 adisposed under the light shield layer 202 is primarily formed using aphoto mask pattern for the light shield layer 202, and the light shieldlayer 202 is then formed on the light absorbing layer 310 a by using thesame mask pattern. Using the same process, the light absorbing layer 310b is primarily formed using a photo mask pattern for forming the gate220, the gate 220 is then formed on the light absorbing layer 310 busing the same mask pattern. A mask pattern for the source/drainelectrode 230 is also used for patterning the light absorbing layer 310c formed under the source/drain electrode 230.

In FIG. 7A, although beams 798 a and 798 b of external light areintroduced into the light absorbing layers 310 a and 310 c, only a smallquantity of beams 799 a and 799 b of light is reflected due to physicalcharacteristics of the light absorbing layer 310 a and 310 c.

FIG. 7B illustrates a structure of a thin-film transistor where theaforementioned light absorbing layer 310 and the aforementioned phasecompensation layer 320 are disposed. Phase compensation layers 320 a,320 b and 320 c are formed under the light absorbing layers 310 a, 310 band 310 c, and are formed of an oxide having a high reflectance, such asSiNx, ITO, IZO, IGZO, etc. The phase compensation layers 320 a, 320 band 320 c may be formed to have the same aforementioned pattern as thatof the light absorbing layers 310 a, 310 b, and 310 c. That is, thephase compensation layers may use a pattern to be used to form a metalmaterial at a location where each of them are formed, according to thecorresponding location. For example, the phase compensation layer 320 adisposed under the light shield layer 202 is primarily formed using aphoto mask pattern for the light shield layer 202, the light absorbinglayer 310 a is formed using the same mask pattern, and the light shieldlayer 202 is formed thereon. Using the same process, the phasecompensation layer 320 b is primarily formed using a photo mask patternfor forming the gate 220, the light absorbing layer 310 b is formedusing the same mask pattern, and the gate 220 is then formed thereon. Amask pattern for the source/drain electrode 230 is also used forpatterning the phase compensation layer 320 c and the light absorbinglayer 310 c formed under the source/drain electrode 230.

In FIG. 7B, although beams 798 a and 798 b of light are introduced intothe light absorbing layers 310 a and 310 c, only a very small quantityof beams 799 a and 799 b of light is reflected due to physicalcharacteristics of the light absorbing layers 310 a and 310 c. Further,the small quantity of light also provides an effect that cancels theintroduced beams 798 a and 798 b of light due to the phase compensationlayers 320 a and 320 c.

The present invention may be implemented such that an oxide having ahigh reflectance may be used for forming the phase compensation layer,examples of the oxide having a high reflectance correspond to materialssuch as SiNx, ITO, IZO, IGZO, etc., and the thickness of the phasecompensation layer is 1000 Å or thinner. Likewise, the present inventionmay be also implemented such that the thickness of the light absorbinglayer is also 1000 Å or thinner and the thickness of a portion obtainedby summing the phase compensation layer and the light absorbing layer is1000 Å or thinner.

In summary, as shown in FIGS. 7A and 7B, a single oxide or an alloyoxide having a faction of a light absorption and a phase differenceinterference is deposited on a metal wire, thereby reducing areflectance of external light input to a display panel in which apolarizing plate or a polarizing film is not included.

The above-mentioned light absorbing layer and the phase compensationlayer according to an embodiment of the present invention reduces areflectance of external light which is non-polarized light and removesthe external light through a phase compensation. Table 1 shows areflectance when the light absorbing layer includes a copper oxide andthe phase compensation layer includes SiNx under a metal wire.

TABLE 1 Classificaion Edge Center Average reflectance (%) 5.1 4.9

As shown in Table 1, the reflectances of an edge portion and a centerportion of a panel are 5.1% and 4.9%, respectively. It is identifiedthat a very small part of light introduced from the outside isreflected.

The total thickness D of the light absorbing layer and the phasecompensation layer may be determined by controlling as described belowin order to obtain a low reflection of external light through anabsorption of visible light and a phase different interference. When thetotal thickness is controlled as described below, the thickness which isproper for a wavelength of the external light and a characteristic ofthe deposited light absorbing layer may be selected, thereby improving alight absorbing efficiency and a low reflection effect

Equation  1                                       $\begin{matrix}{D = \frac{\lambda}{4n}} & (1)\end{matrix}$

Here, ‘n’ is a refractive index of the light absorbing layer. When thelight absorbing layer includes a material of which a refractive index is2.0 (i.e., n=2.0), the total thickness of the light absorbing layer forthe low reflection and the phase compensation layer may be equal to orthinner than 1 μm (1000 Å) in consideration of the wavelength of theexternal light, the refractive index of the light absorbing layer, andthe like. More specifically, in order to increase a light absorptioneffect, the thickness may be 500 to 1000 Å. According to Equation 1, thethickness of the phase compensation layer may be proportional to thewavelength of the external light, and inversely proportional to therefractive index of the light absorbing layer. The above-mentionedEquation 1 is for calculating an optical destructive interference forreducing a reflection when a single thin-film exists, but the presentinvention is not limited thereto. That is, in order to reduce areflectance, various thicknesses may be selectively applied.

When the thicknesses of the light absorbing layer and the phasecompensation layer are controlled, a light absorbing ratio for theexternal light and an effect of a phase compensation can be increased.This is described above with reference to FIGS. 3 to 7B.

In more detail, the reflectance according to the existence-or-not of thelight absorbing layer and the phase compensation layer will be describedwith reference to the following Table 2.

TABLE 2 Reflectance for each thickness of light absorbing layer and eachthickness of phase compensation layer Thickness Thickness when Thicknesswhen of phase light absorbing layer light absorbing layer compensationis formed of CuOx is formed of MoTi Reflectance layer (Å) (Å) (Å) (%)None 600 300 7.5 None 500 300 7.8 400 (IGZO) 600 300 5.4 400 (IGZO) 500300 5.0 300 (SiNx) 600 300 5.3 300 (SiNx) 500 300 4.9

FIG. 8 is a graph depicting relationships between a reflectance and awavelength according to an embodiment of the present invention and therelated art.

A first embodiment is a case wherein a light absorbing layer and a phasecompensation layer are formed in a metal line. The metal line includesan alloy of Cu/MoTi, the light absorbing layer includes CuOx, and thephase compensation layer includes SiNx. A reflectance is 4.9% in allwavelength bands.

A second embodiment is a case wherein the light absorbing layer isformed in the metal line. The metal line includes an alloy of Cu/MoTi,and the light absorbing layer includes CuOx. The reflectance is somewhathigh in a low wavelength band, the reflectance is equal to or lower thanthat of the first embodiment in 500 to 700 nm area, and an averagereflectance is 6.3%.

In the prior art, a reflectance of external light is 43%. In summary,when the light absorbing layer and the phase compensation layer areselectively deposited on the metal line, the reflectance of the externallight is reduced from 4.3% to 4.9%.

As described with Equation 1 and Table 2 above, the thickness of thelight absorbing layer in the first and second embodiments may be set tobe 1 μm or below. The thickness may be set to be 1 μm or below (i.e.equal to or thinner than 1000 Å) in consideration of a wavelength of theexternal light, a refractive index of the light absorbing layer, and thelike. In order to increase a light absorbing effect, the thickness maybe 500 to 1000 Å. This may be applied to all of the light absorbinglayers according to an embodiment of the present invention describedwith reference to FIGS. 3 to 7B.

The display panel including the light absorbing layer described abovemay include a multi-layered light absorbing layer in the gate line andthe data line. Multiple layers including a 1-1 metal layer for a gateand a line, and a second metal layer for the light absorbing layer maybe formed as the gate line. In addition, multiple layers including a 1-2metal layer for a source electrode, a drain electrode and a line, and asecond metal layer for the light absorbing layer may be formed as thedata line. That is, when the present invention is applied, the multiplelayers of gate line and the data lines with which the light absorbinglayer is combined form the thin-film transistor, and thus the lightabsorbing layer combined with the thin-film transistor and the lines canabsorb external light.

In summary, the display panel according to the present inventionincludes multiple layers of a data line including a light absorbinglayer and multiple layers of a gate line including the light absorbinglayer, a plurality of thin-film transistors formed due to intersectionsof the data lines and the gate lines, a light shield layer facing thethin-film transistor, a plurality of pixel electrodes connected to asource electrode or a drain electrode of the thin-film transistor, andan organic light emitting layer facing the pixel electrode. The presentinvention provides an effect of absorbing an external light which isnon-polarized light because a light absorbing layer is combined with athin-film transistor and a line in multiple layers.

Meanwhile, the light shield layer may also include a light absorbinglayer. The light shield layer may be a single layer structure includinga light absorbing material, or may be a dual layer or multiple layerstructure in which the light absorbing layer is combined with the lightshield layer. When the light shield layer includes only the lightabsorbing material, a process of depositing a separate light absorbinglayer may be omitted.

FIG. 9 is a flowchart illustrating a process of forming a lightabsorbing layer on a light shield layer and a wiring area according toan embodiment of the present invention. The process of FIG. 9 may beapplied to a bottom emission of FIG. 7A, but the present invention isnot limited thereto, and may be applied to all processes forming a lightabsorbing layer for a low reflection before forming a wire layer.

Firstly, a substrate is arranged (S910). Next, a first light absorbinglayer is formed using a mask (i.e., a first mask). The first lightabsorbing layer may be the light absorbing layer 310 a described above.A light shield layer is formed on the first light absorbing layer usingthe mask (i.e. the first mask) for forming the light shield layer(S925). A buffer layer is formed (S930). An active layer is formed onthe buffer layer (S940). Next, a gate insulation layer is formed using amask (i.e. a second mask) for forming a gate (S950). Next, a secondlight absorbing layer is formed using the mask which is the second maskfor forming the gate (S952). After the second light absorbing layer isformed, the gate is formed on the second light absorbing layer using themask for forming the gate (S955). Next, an interlayer dielectric isformed (S960). Next, as shown in FIGS. 5A to 5C, a third light absorbinglayer is formed using a mask (i.e. a third mask) for forming a sourceelectrode and a drain electrode (S970). The third light absorbing layer,the interlayer dielectric and the buffer layer are etched, and contactholes are formed through the third light absorbing layer, the interlayerdielectric and the buffer layer (S972). Next, the source electrode andthe drain electrodes are formed using the third mask for forming thesource electrode and the drain electrode (S975). After the thin-filmtransistor is formed, processes such as connecting the thin-filmtransistor with a pixel electrode (i.e. an anode electrode) and forminga light emitting layer and a color filter are progressed. A protectionlayer is formed. A manufacturing of a panel is completed.

Although not shown in FIG. 9, a phase compensation layer may further beformed before forming the first, second and third light absorbinglayers. In this case, the phase compensation layer may be deposited oneach of the first, second and third light absorbing layers using thefirst, second and third masks. A destructive interference occurs betweenreflected external light and incident external light due to the phasecompensation layer, thereby removing the reflected external light.

In addition, as another embodiment, a function of the phase compensationlayer may be combined to the first, second and third light absorbinglayers. Alternatively, the phase compensation layer and the first,second and third light absorbing layers may be formed simultaneously.

The mask which absorbs the external light is formed in each of the wireareas and metal material areas using the mask necessary in forming thelight shield layer, gate, source/drain electrodes through the process ofFIG. 9, thereby reducing a cost for an additional mask. In addition, theexternal light which is non-polarized light is absorbed, therebyreducing a cost consumed in depositing a polarizing plate and apolarizing film on a panel and increasing a light efficiency of a panel.

When the embodiment of the present invention is implemented, a lowreflection metal wire can be formed and visibility of an organic lightemitting display device can be improved through a process of depositinga simple metal or an alloy oxide, such as a copper oxide. Especially, areflectance in a display panel where a polarizing plate/polarizing filmfor polarizing external light are not included may be determined as acombination of reflectances of an opening portion and a non-openingportion. In this case, a wire reflectance of the non-opening portionwhere the embodiment of the present invention is not applied is about40%. However, when the present invention is applied, the reflectance ofthe non-opening portion can be reduced as described with reference toFIG. 8.

In the prior art, in order to reduce a reflectance of an external lightin a metal wire area, a low reflection technique is implemented bycoating a Black Matrix (BM), and this incurs a problem of forming theBM. However, when the present invention is applied, the presentinvention proposes a technique for implementing a low reflection in anOLED wire part using only a process of depositing a metal oxide or analloy oxide having a thickness (500 to 1000 Å) of 1 μm or below, that isa thickness of a wavelength of visible light, thereby improvingvisibility of an organic light emitting display device. In addition, apolarizing plate or a polarizing film is removed, thereby improvingefficiency of a display panel and a lifetime of a device.

While the technical spirit of the present invention has been exemplarilydescribed with reference to the accompanying drawings, it will beunderstood by a person skilled in the art that the present invention maybe varied and modified in various forms without departing from the scopeof the present invention. Accordingly, the embodiments disclosed in thepresent invention are merely to not limit but describe the technicalspirit of the present invention. Further, the scope of the technicalspirit of the present invention is not limited by the embodiments. Thescope of the present invention shall be construed on the basis of theaccompanying claims in such a manner that all of the technical ideasincluded within the scope equivalent to the claims belong to the presentinvention.

What is claimed is:
 1. A method of preparing a display device includinga plurality of pixels where a plurality of gate lines cross a pluralityof data lines, respectively, each of the pixels including a thin filmtransistor (TFT) region and a display region, the method comprising:forming a thin film transistor (TFT) in the TFT region; and forming alight emitting element for displaying images based on signals from theTFT in the display region, wherein a metallic layer is disposed in theTFT region for electrical connection of the TFT, and wherein a lightabsorbing layer configured to absorb at least part of light propagatingtoward the metallic layer is disposed on the metallic layer between themetallic layer and one of a gate insulating layer, an active layer, aninterlayer dielectric layer and a substrate.
 2. The method of claim 1,wherein the metallic layer is a gate electrode of the TFT.
 3. The methodof claim 1, wherein the metallic layer is at least one of source anddrain electrodes of the TFT.
 4. The method of claim 1, wherein themetallic layer is a light shield layer disposed between the TFT and thelight absorbing layer.
 5. The method of claim 1, wherein a phasecompensation layer configured to adjust a phase of the light is disposedon the light absorbing layer, and wherein the light absorbing layer isdisposed between the gate electrode and a gate insulation layer of theTFT.
 6. The method of claim 1, wherein the metallic layer and the lightabsorbing layer are formed using a same mask.
 7. The method of claim 5,wherein the metallic layer, the light absorbing layer, and the phasecompensation layer are formed using a same mask.
 8. A method ofpreparing a display device including a plurality of pixels where aplurality of gate lines cross a plurality of data lines, respectively,each of the pixels including a thin film transistor (TFT) region and adisplay region, the method comprising: forming a thin film transistor(TFT) in the TFT region; and forming a light emitting element fordisplaying images based on signals from the TFT in the display region,wherein a metallic layer is disposed in the TFT region for electricalconnection of the TFT, wherein a light absorbing layer is disposed onthe metallic layer and configured to absorb at least part of lightpropagating toward the metallic layer, and wherein the metallic layerand the light absorbing layer are formed using a same mask pattern. 9.The method of claim 8, wherein the metallic layer is one of a gateelectrode of the TFT, and a light shield layer disposed between the TFTand the light absorbing layer.
 10. The method of claim 8, wherein themetallic layer is at least one of source and drain electrodes of theTFT, or is an electric connection wire or electrode of the TFT.
 11. Themethod of claim 8, wherein the metallic layer is a light shield layerdisposed between the TFT and the light absorbing layer.
 12. The methodof claim 8, further comprising a phase compensation layer configured toadjust a phase of the light propagating toward the metallic layer anddisposed on the light absorbing layer.
 13. The method of claim 8,wherein the light absorbing layer includes two or more of a copperoxide, a nickel oxide, a molybdenum oxide, and copper/nickel/molybdenum.14. The method of claim 12, wherein the phase compensation layerincludes at least one of SiN, IGZO, and ITO.
 15. The method of claim 12,wherein the metallic layer, the light absorbing layer, and the phasecompensation layer are formed using a same mask.
 16. A method ofpreparing a display device including a plurality of pixels where aplurality of gate lines cross a plurality of data lines, respectively,each of the pixels including a thin film transistor (TFT) region and adisplay region, the method comprising: forming a thin film transistor(TFT) in the TFT region; and forming a light emitting element fordisplaying images based on signals from the TFT in the display region,wherein a metallic layer is disposed in the TFT region for electricalconnection of the TFT, wherein a light absorbing layer is disposed onthe metallic layer and configured to absorb at least part of lightpropagating toward the metallic layer, and wherein a phase compensationlayer is configured to adjust a phase of the light propagating towardthe metallic layer and disposed on the light absorbing layer.
 17. Themethod of claim 16, wherein the metallic layer is a gate electrode ofthe TFT, at least one of source and drain electrodes of the TFT, or alight shield layer disposed between the TFT and the light absorbinglayer.
 18. The method of claim 16, wherein the phase compensation layerincludes at least one of SiN, IGZO, and ITO.
 19. The method of claim 18,wherein a thickness of the phase compensation layer is proportional to awavelength of the light and is inversely proportional to a refractiveindex of the light absorbing layer.
 20. The method of claim 16, whereinthe metallic layer, the light absorbing layer, and the phasecompensation layer are formed using a same mask.